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Source Code Review Grep Script

As a pentester you sometimes get access to the source code of the application you are reviewing. Sometimes you can look manually through the files, but sometimes you get million lines of code and you don’t have time to spend sitting there, reading line after line.

The first approach that came to my mind was to use static code analysis tools. There are a lot of them out there, you can find lists of tools on the flawfinder page or you can have a look at Wikipedia’s list of tools for static code analysis. It definitely makes sense to use these tools, but it needs time to download/compile them and most of them are written for one particular language.

You will be reading a lot of code. If you want to do yourself a favour, use an IDE like eclipse to look at the code. Especially when looking at Java code you will find yourself quite often changing from one class to another and changing between files. With eclipse you only need one click for that. But still, you need different IDEs for different programming languages. So this is still not a universal approach.

As a penetration tester you often want to find the interesting parts of the code. To name some interesting things: everything related to cryptography, encryption, SQL queries, file read and writes, URLs and sockets, obfuscation, passwords and so on. And there is one really universal tool that let us find these parts of the code: grep.

The script I wrote here is pretty focused on Java/Android and Objective-C/iOS. But I also got some JSP and spring java framework specific code. So here we go, no rocket science, but I hope it’s helpful for someone in the future.

Of course the script produces a lot of false positives, but it should be a tool that supports you in your manual analysis. I’m sure there are a million more interesting strings we can add to the script. If you think something is missing, leave it in the comments and I’ll add it.

Oh and if you already looked at one version of a source code and you get a new version, you better use the “diff” command line tool and first have a look at the parts that changed.